Sarri's side quickly set about quietening the vociferous home support and within seven minutes Willian succeeded, his low shot somehow squirming under Alexandros Paschalakis' body.

Morata should have doubled Chelsea's lead soon after, but his problems in front of goal continued as he inexplicably headed wide from six yards.

The Spaniard wasted another five chances before the break as Chelsea failed to turn their domination into a healthy lead, Pedro also guilty of spurning a gilt-edged opportunity.

Marcos Alonso and Antonio Rudiger both failed to convert on the hour as Chelsea's control of proceedings continued, the latter unable to tap home from Barkley's front-post flick.

Even the introduction of last-season's top scorer Aleksandar Prijovic could not spark PAOK into action, the substitute having to live off scraps as the hosts struggled to make an impact.

Cesc Fabregas made a welcome return from a knee injury midway through the second half, while Morata's frustrating night ended with 10 minutes to play when he was replaced by Olivier Giroud.

What does it mean: No stopping Sarri

Many questioned how Chelsea would adapt to life under Sarri given the differences in his management style compared to Antonio Conte, but it seems they had no need to worry. It is now a six-match winning streak for the Italian, who has never lost a Europa League group match.

Pat on the back: Barkley brims with confidence

Barkley's fine display in midfield will have pleased Sarri and not gone unnoticed by England boss Gareth Southgate. The 24-year-old showed nice touches throughout, linked the play well and provided a fine assist for Willian – just the kind of creativity Southgate's Three Lions have been missing.

Boot up the backside: More Morata misery

When things are not going your way, the ball will just not go in. That must be how Morata is feeling at the moment. The forward was lively for the visitors, but his bad luck in front of goal continues. He might have had a first-half hat-trick, but looks short on confidence..

Morata has the ball in the back of net but up goes the assistant referee's flag.

- Each of Chelsea's last 10 managers have won their first European game in charge of the club, with Claudio Ranieri the last to fail to do so in September 2000 (0-2 v FC St Gallen).
- Chelsea have won each of their last four games in the Europa League, a run which includes their final three games in 2012-13 when they won the competition.
- Chelsea manager Maurizio Sarri has won 100 per cent of his group stage games in the Europa League (7/7), keeping five clean sheets in this run.
- PAOK have failed to score in six of their last seven home games in the Europa League.
- Willian has been directly involved in 13 goals in his last 15 starts for Chelsea in European competition (10 goals, 3 assists).
- Ross Barkley's assist for Chelsea's opening goal was his first in club football since April 2017 for Everton against Leicester.

What's next?

Sarri's Blues return to league action on Sunday with a London derby at West Ham, while PAOK entertain AEK Athens in what is bound to be a fiery encounter. Their last meeting saw PAOK chairman Ivan Savvidis storm the pitch carrying a gun – an action that led to AEK being handed the win and PAOK deducted points, which ultimately cost them the league to AEK's benefit.